Relatively recently they updated their policy. If you don't login to your account for two years they will delete everything. Source: https://support.google.com/accounts/answer/12418290?hl=en

I have two accounts from my youth with mostly fansubs and "funny" vids. (A "Everybody Draw Mohammed Day"-Video that, 11 years after its upload, got band in Pakistan.) It includes two very successful (over 1M views combined) uploads of political TV shows. I will not log in to this this accounts. So this stuff will get deleted. So in the long run, stuff will disappear from YT.